WFIRST

The Wide Field Infrared Survey Telescope

WFIRST is a NASA observatory designed to perform Wide Field imaging and surveys of the near infrared (NIR) sky. The current design of the mission makes use of an existing 2.4m telescope, which is the same size as the Hubble Space Telescope. WFIRST is the top-ranked large space mission in the New Worlds, New Horizon Decadal Survey of Astronomy and Astrophysics. The Wide Field Instrument will provide a field of view of the sky that is 100 times larger than images provided by HST. The coronagraph will enable astronomers to detect and measure properties of planets in other solar systems.

The Wide-Field Infrared Survey Telescope (WFIRST) is an upcoming space telescope designed to perform wide-field imaging and spectroscopy of the infrared sky. One of WFIRST’s objectives will be looking for clues about dark energy—the mysterious force that is accelerating the expansion of the universe. Another objective of the mission will be finding and studying exoplanets.
WFIRST uses the same 2.4 meter telescope size as Hubble, but with 18 cutting-edge fourth-generation image sensors compared to Hubble's single first-generation sensor. As a result, each WFIRST image will cover over 200 times as much as a Hubble Wide Field Camera 3/IR image and be 300 megapixels in size. Hubble images reveal thousands of galaxies; a single WFIRST image will uncover millions.

NASA officially is beginning work on an astrophysics mission designed to help unlock the secrets of the universe -- the Wide Field Infrared Survey Telescope (WFIRST).
With a view 100 times bigger than that of NASA’s Hubble Space Telescope, the Wide Field Infrared Survey Telescope WFIRST will aid researchers in their efforts to unravel the secrets of dark energy and dark matter, and explore the evolution of the cosmos. It also will discover new worlds outside our solar system and advance the search for worlds that could be suitable for life.
WFIRST is the agency's next major astrophysics observatory, following the launch of the James Webb Space Telescope in 2018. The observatory will survey large regions of the sky in near-infrared light to answer fundamental questions about the structure and evolution of the universe, and expand our knowledge of planets beyond our solar system – known as exoplanets.

The Wide-Field Infrared Survey Telescope (WFIRST) is an upcoming space telescope designed to perform wide-field imaging and spectroscopy of the infrared sky. One of WFIRST’s objectives will be looking for clues about dark energy—the mysterious force that is accelerating the expansion of the universe. Another objective of the mission will be finding and studying exoplanets.
WFIRST uses the same 2.4 meter telescope size as Hubble, but with 18 cutting-edge fourth-generation image sensors compared to Hubble's single first-generation sensor. As a result, each WFIRST image will cover over 200 times as much as a Hubble Wide Field Camera 3/IR image and be 300 megapixels in size. Hubble images reveal thousands of galaxies; a single WFIRST image will uncover millions.
To help uncover the mystery of dark energy, WFIRST will make incredibly precise measurements of the universe. These measurements, like the distance and position of galaxies, can be compared to other measurements—such as the cosmic microwave background from the WMAP mission—to determine how dark energy has changed over time. WFIRST can also measure the slight distortions in light from distant galaxies as it passes more nearby mass concentrations. These data will build a three dimensional picture of how mass is distributed throughout the universe, and provide independent confirmation of its structure.
Because WFIRST has such a large and sensitive field of view, it can find thousands of new exoplanets through a process called microlensing. When one star in the sky appears to pass nearly in front of another, the light rays of the background source star become bent due to the gravitational "attraction" of the foreground star. This "lens" star is then a virtual magnifying glass, amplifying the brightness of the background source star. If the lens star harbors a planetary system, then those planets can also act as lenses, each one producing a short deviation in the brightness of the source. For closer planets, WFIRST will open a new era of direct observation. Currently only a handful of planets are observable in light reflected off of them, and they are all large planets close to their stars. WFIRST will be able to detect planets as small as Neptune, and as far from their stars as Saturn is from the sun. This is possible thanks to newly developed coronagraphs, which block the bright light from the star to make the planet more visible.

NASA officially is beginning work on an astrophysics mission designed to help unlock the secrets of the universe -- the Wide Field Infrared Survey Telescope (WFIRST).
With a view 100 times bigger than that of NASA’s Hubble Space Telescope, the Wide Field Infrared Survey Telescope WFIRST will aid researchers in their efforts to unravel the secrets of dark energy and dark matter, and explore the evolution of the cosmos. It also will discover new worlds outside our solar system and advance the search for worlds that could be suitable for life.
WFIRST is the agency's next major astrophysics observatory, following the launch of the James Webb Space Telescope in 2018. The observatory will survey large regions of the sky in near-infrared light to answer fundamental questions about the structure and evolution of the universe, and expand our knowledge of planets beyond our solar system – known as exoplanets.
It will carry a Wide Field Instrument for surveys, and a Coronagraph Instrument designed to block the glare of individual stars and reveal the faint light of planets orbiting around them. By blocking the light of the host star, the Coronagraph Instrument will enable detailed measurements of the chemical makeup of planetary atmospheres. Comparing these data across many worlds will allow scientists to better understand the origin and physics of these atmospheres, and search for chemical signs of environments suitable for life.
The telescope’s sensitivity and wide view will enable a large-scale search for exoplanets by monitoring the brightness of millions of stars in the crowded central region of our galaxy. The survey will net thousands of new exoplanets similar in size and distance from their star as those in our own solar system, complementing the work started by NASA's Kepler mission and the upcoming work of the Transiting Exoplanet Survey Satellite.
Employing multiple techniques, astronomers also will use WFIRST to track how dark energy and dark matter have affected the evolution of our universe. Dark energy is a mysterious, negative pressure that has been speeding up the expansion of the universe. Dark matter is invisible material that makes up most of the matter in our universe.
By measuring the distances of thousands of supernovae, astronomers can map in detail how cosmic expansion has increased with time. WFIRST also can precisely measure the shapes, positions and distances of millions of galaxies to track the distribution and growth of cosmic structures, including galaxy clusters and the dark matter accompanying them.
WFIRST is slated to launch in the mid-2020s. The observatory will begin operations after traveling to a gravitational balance point known as Earth-Sun L2, which is located about one million miles from Earth in a direction directly opposite the Sun.
WFIRST is managed at Goddard, with participation by the Jet Propulsion Laboratory (JPL) in Pasadena, California, the Space Telescope Science Institute in Baltimore, the Infrared Processing and Analysis Center, also in Pasadena, and a science team comprised of members from U.S. research institutions across the country.

WFIRST, the Wide Field InfraRed Survey Telescope, is a NASA observatory designed to settle essential questions in the areas of dark energy, exoplanets, and infrared astrophysics. The telescope has a primary mirror that is 2.4 meters in diameter (7.9 feet), and is the same size as the Hubble Space Telescope's primary mirror. WFIRST will have two instruments, the Wide Field Instrument, and the Coronagraph Instrument.
The Wide Field Instrument will have a field of view that is 100 times greater than the Hubble infrared instrument, capturing more of the sky with less observing time. As the primary instrument, the Wide Field Instrument will measure light from a billion galaxies over the course of the mission lifetime. It will perform a microlensing survey of the inner Milky Way to find ~2,600 exoplanets.

The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is energy that travels and spreads out as it goes – the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. The other types of EM radiation that make up the electromagnetic spectrum are microwaves, infrared light, ultraviolet light, X-rays and gamma-rays.

In the early 1990s, one thing was fairly certain about the expansion of the Universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the Universe had to slow. The Universe is full of matter and the attractive force of gravity pulls all matter together. Then came 1998 and the Hubble Space Telescope (HST) observations of very distant supernovae that showed that, a long time ago, the Universe was actually expanding more slowly than it is today. So the expansion of the Universe has not been slowing due to gravity, as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it.
Eventually theorists came up with three sorts of explanations. Maybe it was a result of a long-discarded version of Einstein's theory of gravity, one that contained what was called a "cosmological constant." Maybe there was some strange kind of energy-fluid that filled space. Maybe there is something wrong with Einstein's theory of gravity and a new theory could include some kind of field that creates this cosmic acceleration. Theorists still don't know what the correct explanation is, but they have given the solution a name. It is called dark energy.

Planck data reveals that the universe's contents include 4.9% ordinary matter, or atoms, the building blocks of stars and planets. Dark matter comprises 26.8% of the universe. This matter, different from atoms, does not emit or absorb light. It has only been detected indirectly by its gravity. 68.3% of the universe, is composed of "dark energy", that acts as a sort of an anti-gravity. This energy, distinct from dark matter, is responsible for the present-day acceleration of the universal expansion.

Because scientists can't see dark matter directly, they have found other ways to investigate it. We can use indirect ways to study things, like looking at a shadow and making an educated guess about what's casting the shadow. One way scientists indirectly study dark matter is by using gravitational lensing.
Light going through a gravitational lens is similar to light going through an optical lens: It gets bent. When light from distant stars passes through a galaxy or cluster, the gravity of the matter present in the galaxy or cluster causes the light to bend. As a result, the light looks like it is coming from somewhere else rather than from its actual origin. The amount of bending helps scientists learn about the dark matter present.

A representation of the evolution of the universe over 13.77 billion years. The far left depicts the earliest moment we can now probe, when a period of "inflation" produced a burst of exponential growth in the universe. (Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe.

Exoplanets

WFIRST will advance our understanding of exoplanets, provide a comprehensive view of the formation, evolution, and physical properties of planetary systems, and lay the foundation for, the discovery and characterization of a habitable Earth-like planet orbiting a nearby star.

Gravitational microlensing is an observational effect that was predicted in 1936 by Einstein using his General Theory of Relativity. When one star in the sky appears to pass nearly in front of another, the light rays of the background source star become bent due to the gravitational "attraction" of the foreground star. This star is then a virtual magnifying glass, amplifying the brightness of the background source star, so we refer to the foreground star as the lens star. If the lens star harbors a planetary system, then those planets can also act as lenses, each one producing a short deviation in the brightness of the source. Thus we discover the presence of each exoplanet, and measure its mass and separation from its star. This technique will tell us how common Earth- like planets are, and will guide the design of future exoplanet imaging missions.
More than 20 planets have been discovered from the ground using this technique. The WFIRST microlensing survey will detect many more such planets, including smaller mass planets since the planet "spike" will be far more likely to be observed from a space-based platform. This will lead to a statistical census of exoplanets with masses greater than a tenth of the Earth's mass from the outer habitable zone out to free floating planets. The results from the WFIRST microlensing survey will complement the exoplanet statistics from Kepler, and will provide answers to questions about planet formation, evolution, and the prevalence of planets in the galaxy.

A coronagraph works by blocking the bright light of a star to allower dimmer objects, like orbiting exoplanets, to become visible. This in turn allows cameras to directly image the exoplanet.
Direct imaging provides the critical approach to studying the detailed properties of exoplanets. Images and spectra of directly imaged planets provide some of the most powerful information about the structure, composition, and physics of planetary atmospheres. This information can in turn help scientists better understand the origin and evolution of these systems. The direct imaging technique is also naturally applicable to the nearest and brightest, and thus best-characterized, solar systems.
Advancing the technology for direct imaging of exoplanets was the top priority medium-scale space investment recommended by NWNH. Coronagraphy on WFIRST will be a major step towards the long-term goal of a mission that can image habitable Earth-mass planets around nearby stars and measure their spectra for signs of life.

The first exoplanets to be discovered were gas giants, but today it is becoming clear that there are probably many more "small" planets, in the Earth to Super-Earth range, than there are giants. Discovering the statistics of these planets is crucial for understanding their formation and commonality. Gravitational microlensing is a method of finding exoplanets by watching for when their gravity slightly magnifies the light from background stars. This technique will tell us how common Earth- like planets are, and will guide the design of future exoplanet imaging missions.
More than 20 planets have been discovered from the ground using this technique. The WFIRST microlensing survey will detect many more such planets, including smaller mass planets since the planet "spike" will be far more likely to be observed from a space-based platform. This will lead to a statistical census of exoplanets with masses greater than a tenth of the Earth's mass from the outer habitable zone out to free floating planets. The results from the WFIRST microlensing survey will complement the exoplanet statistics from Kepler, and will provide answers to questions about planet formation, evolution, and the prevalence of planets in the galaxy.